Generally, when a spring load is applied on a spring-receiving member for a suspension spring formed of, for example, an elastic material, a deformation of the spring-receiving member cannot sufficiently follow a deformation of the suspension spring, which causes a gap to be formed between the suspension spring and the spring-receiving member.
If foreign matter such as sand or gravel enters the gap formed in such a situation, coating film of the suspension spring may wear out to cause a base surface of the suspension spring to be exposed, resulting in an occurrence of corrosion and breakage of the suspension spring. This phenomenon occurs more frequently around a lower-side spring-receiving member than an upper-side spring-receiving member.
PTL1 describes “an elastic sheet that can prevent a coil spring from, for example, being chipped in its coating or being broken as a result of the entry of mud, sand, or the like” (see the summary and paragraph [0030] of PTL1 (paragraph 0034 of US corresponding application).